Modern mobile communications have a growing tendency to provide users with multimedia services with high transmission rate. FIG. 1 provides system architecture of System Architecture Evolution (SAE), in which,
User equipment (UE) 101 is a terminal device used for receiving data. Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) 102 is a wireless access network, including a macro base station (eNodeB/NodeB) providing an interface to the UE for accessing the wireless network. Mobility Management Entity (MME) 103 is responsible for managing mobile context, session context and security information of the UE. Serving Gateway (SGW) 104 is mainly responsible for providing user plane functions. The MME 103 and the SGW 104 may be deployed in a same physical entity. Packet Data Gateway (PGW) 105 is responsible for functions such as charging and legal monitoring and may be in the same physical entity with the SGW 104. Policy and Charging Rules Function (PCRF) 106 provides Quality of Service (QoS) polices and charging rules. Serving GPRS Support Node (SGSN) 108 is a network node device in Universal Mobile Telecommunications System (UMTS) for providing routes for data during transmission. Home Subscriber Server (HSS) 109 is a home subscriber sub-system of the UE, responsible for protecting user information of the user equipment such as current location, location of a serving-node, user security information, and packet data context of the user equipment.
The interface between the eNB and the MME is an S1 interface. The interface between eNBs is an X2 interface.